CN115022415B

CN115022415B - Multi-layer SID message termination method and device

Info

Publication number: CN115022415B
Application number: CN202210575611.3A
Authority: CN
Inventors: 陈龙; 张聪; 张广治; 周志鹏
Original assignee: Fiberhome Telecommunication Technologies Co Ltd
Current assignee: Fiberhome Telecommunication Technologies Co Ltd
Priority date: 2022-05-23
Filing date: 2022-05-23
Publication date: 2023-08-25
Anticipated expiration: 2042-05-23
Also published as: CN115022415A

Abstract

The application relates to a method and a device for terminating a multilayer SID message, which are characterized by comprising the following steps: constructing termination pair information and storing the termination pair information in a reserved field in a message, wherein the termination pair information comprises the number of SID layers needing termination and a SL starting value of a termination SID; and carrying out SID termination on the information according to the termination to realize that all SIDs needing termination are covered through one-time table lookup. The application can improve the efficiency of the termination flow and reduce the occupation of resources.

Description

Multi-layer SID message termination method and device

Technical Field

The present application relates to the field of communications technologies, and in particular, to a method and an apparatus for terminating a multilayer SID packet.

Background

Currently, in a network SRv (Segment Routing internet protocol version, segment routing based on the sixth version of internet protocol), a message header of a transmitted SRv6 message needs to carry an SRH (Segment Routing Header ), where a Segment List included in the SRH is a path sequence formed by SIDs (Segment Identifier, segment identifiers) of all nodes on a packet forwarding path. Wherein each SID has a standard byte length of 128 bits (bits). In the routing scheme based on SRv network, there are some scenarios where it is required to terminate a multi-layer SID at one station, for example, a certain station in the constraint path needs to terminate the End type first and then terminate the End type and find out the exit, so it is required that a single station continuously terminates a 2-layer SID.

In the related art, when the multi-layer SID message based on SRv6 technology is terminated, each layer of SID is terminated, SL (lower index position pointer of current SID) is reduced by 1, and then the destination IP in the IPv6 message header is replaced; meanwhile, each layer of SID at the end needs to be queried in a local Endpoint SID table, so that the problems of long time consumption, low efficiency and bandwidth occupation are caused. In addition, in some application scenarios, when a single station is required to terminate SIDs with more than seven layers, more than seven termination processes are required to be performed, so that time consumption is doubled, bandwidth is doubled and reduced, and resources of equipment are greatly consumed.

Disclosure of Invention

The embodiment of the application provides a method and a device for terminating a multi-layer SID message, which are used for improving the efficiency of a termination process and reducing the occupation of resources.

In one aspect, the embodiment of the application provides a method for terminating a multi-layer SID message, which is characterized by comprising the following steps:

constructing termination pair information and storing the termination pair information in a reserved field in a message, wherein the termination pair information comprises the number of SID layers needing termination and a SL starting value of a termination SID;

and looking up the information according to the termination and finishing SID termination.

In some embodiments, the reserved field stored in the message includes the steps of:

and storing the number of SID layers to be terminated and the SL start value of the termination SID in the Tags field of the SRH header.

In some embodiments, the termination pair information further includes a termination pair index and a termination enable flag, where the termination pair index is used to specify a preset termination pair, and the termination enable flag is used to determine whether SID termination according to the termination pair information is supported;

the reserved field stored in the message further comprises the steps of:

and storing the termination pair index and the termination enabling mark in the flag field of the SRH header.

In some embodiments, the terminating the information according to the terminating further includes the steps of:

and if the ending enabling mark does not support SID ending of the information according to the ending, SID ending is carried out according to a standard SRv6 ending SID flow.

In some embodiments, the searching the information according to the termination and completing the SID termination includes the steps of:

and if the SL initial value in the termination pair information is the same as the SL value in the SRH header, calculating the SID covered by the termination pair information into a hash value, wherein the hash value is used for searching in a local Endpoint table when the SID is terminated.

In some embodiments, the searching the information according to the termination and completing the SID termination further includes the steps of:

and if the corresponding hash value is found in the local Endpoint table, subtracting the SID layer number to be terminated from SL in the SRH header to obtain the IP address of the last layer of SID covered by the termination pair information, and finishing SID termination by the IP address of the last layer of SID.

In a second aspect, an embodiment of the present application provides a multi-layer SID packet termination device, which is characterized in that it includes:

the terminal pair information construction module is used for constructing terminal pair information and storing the terminal pair information in a reserved field in a message, wherein the terminal pair information comprises the number of SID layers needing to be terminal and a SL initial value of a terminal SID;

and the SID termination module is used for looking up the information according to the termination and finishing SID termination.

In some embodiments, the termination pair information construction module is further configured to:

In some embodiments, the termination pair information includes a termination pair index and a termination enable flag, where the termination pair index is used to specify a preset termination pair, and the termination enable flag is used to determine whether SID termination according to the termination pair information is supported;

the termination pair information construction module is further configured to store the termination pair index and the termination enable flag in the flag field of the SRH header.

In some embodiments, the SID termination module is further configured to:

if the SL initial value in the termination pair information is the same as the SL value in the SRH header, calculating the SID covered by the termination pair information into a hash value, wherein the hash value is used for searching in a local Endpoint table when the SID is terminated;

The technical scheme provided by the application has the beneficial effects that:

the embodiment of the application provides a method and a device for terminating a multi-layer SID message, which are used for identifying a section of SID to be terminated in a constraint path by expanding a reserved field of an SRH header, solving the problems of complex flow, long time consumption, bandwidth occupation and low efficiency caused by the need of repeatedly inquiring a local SID table in a conventional termination flow, shielding the realization difference of different software and hardware schemes, avoiding the need of paying attention to the number of SID layers to be terminated, and being a SRv multi-layer SID message quick termination realization scheme which is easy to push to fall to the ground.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a flow chart of a method for terminating a multi-layer SID message according to an embodiment of the present application;

fig. 2 is a schematic diagram of an SRH header format and a field provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of a segment SRv Policy path passing through a multi-layer SID message termination method according to an embodiment of the present application;

fig. 4 is a schematic diagram of SRv capabilities sub-TLV format provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of a multi-layer SID message termination device according to an embodiment of the present application.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

As shown in fig. 1, a method for terminating a multi-layer SID message includes the steps of:

s100, constructing termination pair information and storing the termination pair information in a reserved field in a message, wherein the termination pair information comprises the SID layer number needing termination and an SL starting value of a termination SID;

and S200, carrying out SID termination on the information according to the termination to realize that all SIDs needing termination are covered through one-time table lookup.

It is understood that the termination pair information is used to reflect information of the SID requiring termination, such as the number of layers of the SID requiring termination and the SL start value at the time of terminating the SID.

In some embodiments, the reserved field stored in the message includes storing the number of SID layers to be terminated and the SL start value of the terminating SID in the Tags field of the SRH header.

It will be appreciated that the two-byte Tags field, which is currently not of particular use, may be utilized to store termination pair information based on the reserved field that is not used by the existing SRH header. Preferably, in the two-byte Tags field, one byte is used to store one termination pair information, such as the number of layers requiring termination is stored in the first 4 bits, and the SL start value at the time of terminating the SID (the SL start value currently requiring termination). Since the Tags field has only 2 bytes, at most two sets of termination pairs can be supported (one termination pair can be understood as a pair of values, as shown in fig. 2, [2,5] is a pair of values, representing one termination pair), and since the maximum value that can be represented by 4 bits is 15, the number of layers that can support termination is 15, and the same SL start value is 15 at most, which is sufficient to support most of the actual application scenarios currently existing. And, the present application does not exclude the use of other reserved fields to achieve more layer number SID terminations.

In some embodiments, the termination pair information includes a termination pair index and a termination enable flag, where the termination pair index is used to specify a preset termination pair, and the termination enable flag is used to determine whether SID termination is supported according to the termination pair information; the reserved field stored in the message also includes a Flags field that stores the termination pair index and the termination enable flag in the SRH header.

It will be appreciated that the end pair index and end enable Flags may be saved with the last 2 bits of the reserved bits in the Flags field of the SRH header on the basis of the reserved field that is not used by the existing SRH header. Specifically, 2 bits after the flag of the SRH header can be sequentially marked as P and T, the 1bit P bit stores the index of the termination pair, when P is 0, the first group of the termination pair is represented, and when P is 1, the second group of the termination pair is represented; the 1bit T bit holds a termination enable flag, which sets 1 to indicate support for SID termination according to the termination pair. Typically the controller may generate the termination pair information based on a global topology and forward it to the head station.

In some embodiments, S200 comprises:

and if the termination enabling mark judges that the SID termination of the information according to the termination is not supported, performing SID termination according to a standard SRv terminal SID flow.

It should be noted that, the standard SRv flow is to subtract 1 from SL for each layer of SID, then replace the destination IP in the IPv6 header, and copy the SID of the current SL location to DIP of the IPv6 header after termination is completed.

It should be noted that, for the corresponding control plane, the issuing node may support or not support SID termination according to the termination pair (whether SRv has a rapid termination capability) by performing an extension protocol control plane packet on an IGP protocol such as IS-IS, for example, adding a t_flag; the support of the node can be reported to the controller through BGP-LS, and when the controller calculates SRv TE path, the controller edits T bit information and other ending pair information in the SRH head according to T_FLAG identification of the node, and issues SRv Policy containing the ending pair information to the head node. If the T_FLAG is not supported, the T bit of the SRv capabilities sub-TLV may be set to 0, i.e., no communication over the protocol is required to other stations in the topology. If other stations in the topology receive SRv capabilities sub-TLV, the quick termination processing is not performed, namely the calculation Hash is not sent to an Endpoint table. Other stations in the topology only send out the issuing Endpoint of Hash after receiving the T set of SRv capabilities sub-TLV.

In some embodiments, S200 comprises:

It will be appreciated that when the device receives a message, it first checks the SL field in the termination pair information and compares it to the SL value in the SRH header, and only if equal, it will continue to terminate according to the termination pair. If the two flows are different, the matching is not successful, and the normal ending flow (the standard SRv flow) is required to be carried out, so that the flow is compatible with the existing SRv flow.

Preferably, when a message is received, checking the T field in the SRH header, comparing the SL start value in the termination pair pointed by the current P bit with the SL value in the SRH header if it is 1, and if it is equal, calculating the SID covered by the termination pair into a 128-bit value by Hash to look up in the local Endpoint table. According to the constraint path, when the control plane is configured, the device adapts the end SID with the T_FLAG and calculates an end Hash value to be issued to a local end list to execute a termination flow. The SL in the SRH header is directly subtracted from the number of layers in the termination pair, and the next flow (End/Endx, etc.) is carried out according to the Endpoint behavior of the outermost SID covered by the termination pair (the behavior of the last SID in the termination pair is taken). Thus, only one flow is needed to complete the tasks that conventional schemes require multiple flows to complete.

In one particular embodiment, as shown in FIGS. 2 and 3, the controller issues SRv Policy containing two sets of termination pair information ([ 2,5], [2,1 ]) to the headend PE1 device and sets { sed [1], sed [2] } constraints P2, { sed [5], sed [6] } constraints PE2.

The last bit of the FLAG field of the SRH header is used to identify whether support is supported according to the termination pair, denoted as T_FLAG, and set 1 indicates support; the penultimate bit is denoted as the P bit, representing the ending pair index, with a P value of 0 or 1. The first 4it in the 2 byte Tags field in the SRH header indicates the number of layers that are terminated; the second 4 bits represent the starting SL value for termination. Taking the first termination pair as an example, 1 byte is [0010,0101], i.e., [2,5], indicating that the layer 2 SID is terminated when SL in the SRH header is 5.

The message passes through P1, inquires that T_FLAG is set, P=0, compares Pair [ P ]. SL=5 with SL=6 in SRH header, and goes through conventional SRv6 termination flow (without terminating according to the termination Pair) if the message is unequal;

the message passes through P2, inquires that T_FLAG is set, P=0, compares Pair [ P ]. SL=5 with SL=5 in SRH header, and walks the fast termination flow (the flow of terminating according to the termination Pair) if equal; hash values are calculated for { sid1, sid2 } terminal pairs. When the control surface is configured below, the same Hash algorithm is adopted for the end SID with the T mark, the 128bit SID is calculated and issued to the end table, so that the user searches in the end table of P2, and if the user searches, the SL subtracts the Pair [ P ]. T; copy SID 2 to IP of IPv6 header, p++ (pseudo code write meaning that the termination of the P bit value plus 1, p=0 position has already been processed for information). If not, normal SRv ends the flow.

P3, P4 go through the normal SRv6 termination flow.

When the message passes through PE2 (the equipment connected with CE, the next station is VPN at the user side), it inquires that T_FLAG is set, P=1, and then comparing Pair [ P ]. SL=1 with SL=1 in SRH header, if equal, going to the fast termination flow, and the table look-up flow is the same as the P2 processing flow; if so, SL subtracts Pair [ P ]. T, and when SL=1, subtracting 2 requires special processing, which means that the last-second-hop SID and VPNSID are continuously popped up, similar to USD pop-up of normal SRv termination flow, if not, normal SRv termination flow is walked.

Regarding the configuration of the fast terminating Endpoint SID entries on P2 and PE2, the T-tagged Endpoint SID issued by the control plane may be computed-Hash value-adapted issued. The behavior of the Endpoint takes the behavior corresponding to the last SID in the termination pair.

As shown in fig. 4, SID information supporting fast termination IS advertised by extending an IGP protocol such as IS-IS on the control plane. Taking IS-IS as an example, SRv capabilities sub-TLV IS extended, T_FLAG IS added, and the advertising node supports the quick termination capability. T_flag is defined by the scheme, and when t_flag is set, indicates that the current node has a fast termination capability, and SRv for identifying the node is fast termination capability (whether termination according to the termination pair is supported).

On the other hand, as shown in fig. 5, an embodiment of the present application further provides a device for terminating a multi-layer SID packet, which is characterized in that it includes:

and the SID termination module is used for carrying out SID termination on the information according to the termination to realize that all SIDs needing termination are covered by one-time table lookup.

In some embodiments, the SID termination module is further configured to terminate the SID according to a standard SRv SID procedure if the termination enable flag determines that the SID termination of the information according to the termination is not supported.

In some embodiments, the SID termination module is further configured to

Those of ordinary skill in the art will appreciate that all or some of the steps, systems, functional modules/units in the apparatus, and methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between the functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed cooperatively by several physical components. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer-readable storage media, which may include computer-readable storage media (or non-transitory media) and communication media (or transitory media).

The foregoing is merely a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto, and any person skilled in the art may easily think of various equivalent modifications or substitutions within the technical scope of the embodiment of the present application, and these modifications or substitutions should be covered in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiments of the present application shall be subject to the protection scope of the claims.

Claims

1. The method for terminating the multi-layer SID message is characterized by comprising the following steps:

2. The method for terminating a multi-layer SID message as defined in claim 1, wherein said reserved fields stored in said message comprise the steps of:

3. The method for terminating a multi-layer SID message as defined in claim 2, wherein said termination pair information further comprises a termination pair index and a termination enable flag, wherein said termination pair index is used for specifying a preset termination pair, and said termination enable flag is used for determining whether SID termination of the information according to said termination pair is supported;

the reserved field stored in the message further comprises the steps of:

4. The method for terminating a multi-layer SID message as recited in claim 3, wherein said terminating information comprises the steps of:

5. A multi-layer SID message termination device, comprising:

the SID termination module is used for calculating the SID covered by the termination pair information into a hash value if the SL starting value in the termination pair information is the same as the SL value in the SRH header, and the hash value is used for searching in a local Endpoint table when the SID is terminated; and if the corresponding hash value is found in the local Endpoint table, subtracting the SID layer number to be terminated from SL in the SRH header to obtain the IP address of the last layer of SID covered by the termination pair information, and finishing SID termination by the IP address of the last layer of SID.

6. The multi-layer SID message termination device of claim 5 wherein said termination pair information construction module is further configured to:

7. The multi-layer SID message termination apparatus as in claim 6, wherein,

the terminal pair information comprises a terminal pair index and a terminal enabling mark, wherein the terminal pair index is used for designating a preset terminal pair, and the terminal enabling mark is used for judging whether SID terminal is supported according to the terminal pair information;

8. The multi-layer SID message termination device of claim 7 wherein said SID termination module is further configured to terminate the SID according to standard SRv termination SID procedures if the termination enable flag does not support SID termination of the information according to said termination.